Gas turbine engine assemblies generally include a combustor that receives pressurized air from a compressor and fuel from a fuel injector. The resulting fuel-air mixture is ignited to produce high temperature combustion gases, which then flow downstream into a turbine for energy extraction. The high temperature gases in the combustor create a temperature environment that may limit the useful operating time, and ultimately, the component life of the combustor and the other components of the engine. Accordingly, cooling of the engine, particularly the combustor, is desired.
Conventional systems and methods for cooling the combustor, such as louvers, have been met with mixed success, at best. It has been found that the introduction of cooling air into the upstream end of the combustor may not be as effective as is normally desirable for a given flow of air. As such, the amount of air for use in the primary combustion process is limited, thereby giving rise to less than efficient combustion. Additionally, carbon deposition may occur, and it is sometimes difficult to limit harmful emissions, e.g., carbon monoxide, unburned hydrocarbons, smoke, and the oxides of nitrogen. These emissions can accumulate and be swept out of the combustion chamber in the cooling air film before the emissions have a chance to be consumed by the combustion process.
Effusion cooling has also been utilized. Effusion cooling generally involves an array of small holes in the combustor wall that admit a layer of cooling air to the inner surfaces of the combustor. The cooling air buffers the inner surfaces from the hot gases of the combustion process. However, conventional effusion cooling techniques may not provide sufficient cooling of the combustor for a given amount of cooling air
Accordingly, it is desirable to provide engine assemblies having combustors with improved temperature management, and it is particularly desirable to provide more effective and efficient effusion cooling techniques for combustors. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.